The relationship between conduct disorder age of onset and comorbid internalizing disorders

M.A. University of Hawaii at Manoa 2012.Includes bibliographical references.Conduct Disorder (CD) is associated with high rates of comorbidity, placing children at increased risk for more complex and impairing psychopathology and more negative long-term outcomes. CD is conceptualized to arise from two distinct developmental pathways (Childhood Onset and Adolescent Onset) based on the timing of the earliest CD symptom. The childhood onset subtype is associated with more physical aggression, higher impairment, longer course and poorer outcomes. While this subtype distinction has proven useful, little is known about age of CD onset and the presence of common comorbid disorders (other than AD/HD). The aims of the current study were: (1) to examine the overall rates of internalizing disorder comorbidity, (2) determine if the presence of internalizing comorbidity is predicted by age of CD onset (3) examine whether age of CD onset continues to predict comorbidity after controlling for gender and level of impairment and (4) determine whether gender moderates any relationships between CD age of onset and internalizing comorbidity. The study sample was drawn from archival data of 250 youth who were referred for emotional and behavior assessments at a university-based child and adolescent mental health clinic from 2000 until 2010 and were assigned a CD diagnosis. Results indicated that the overall rate of comorbidity of the final sample (n= 230) was high, with 177 participants (76.95%), carrying one or more comorbid diagnosis at time of assessment. Eighty-two participants carried one or more internalizing diagnosis (35.65%), of which 34 had a mood disorder without a past or co-occurring anxiety disorder (14.78%) and 32 had an anxiety disorder without a past or co-occurring mood disorder (13.91%). Results consistently indicated that older age of onset predicted the presence of a mood disorder. Generally, younger age of onset tended to be non-significantly associated with the presence of an anxiety disorder. For example, match sample analyses pairing 52 childhood onset subtype participants with 52 randomly selected adolescent onset subtype participants, showed that a younger age of CD onset marginally predicted the presence of an anxiety disorder. Age of onset, or CD subtype did not significantly predict the co-occurrence of anxiety or mood problems on self-reported or parent-reported dimensional measures. No moderator effect was found for gender on the presence of mood or anxiety disorders. However, a substantively small but statistically significant interaction between gender and age of onset was found indicating that the relationship between age of CD onset and selfreported depression symptoms was greater for girls than for boys. To the author's knowledge, no other study has examined whether age of onset (measured dimensionally or categorically via subtype) predicted internalizing comorbidity while limiting the age at time of assessment to adolescents only